In accordance with an earlier invention covered by my U.S. Pat. No. 4,304,257, I disclosed a valve that includes a body member that has a firm and stable support surface and a flexible sheet member that has a surface for conforming and mating with the surface valve body member. There are at least two fluid flow channels in the surface of the body member separated from each other by a land portion. The surface of the land portion is coincident with the surface of the member in which it is formed; in this instance, the "firm and stable support surface" of the valve.
A mechanical actuator is employed to flex the sheet member between a first position in which a surface of the sheet is in mating and sealing engagement with the surface of the body member to block flow between the two channels and a second position in which the sheet surface is spaced from the first position to allow fluid flow across the land surface between the two flow channels.
The firm and stable support surface is disclosed as being flat as is the flexible sheet member that seals the flow channels.
The flexible sheet member is a manifold diaphragm sheet made of polyurethane or silicone and of sufficient thickness such that heads formed on the ends of stems of the mechanical actuators can be embedded in the sheet. This requires the sheet to have substantial thickness. Because the sheet is an elastomer, were it able somehow to be made thinner, it could be gas previous which is undesirable.
The actuators are solenoid operated which are not only bulky but heavy and employ substantial power for actuation. This is somewhat limiting to the function of the valve, particularly when many similar valves are assembled together in a manifold environment. The actuators also require extremely sensitive adjustment.
In accordance with my earlier invention, the flexible sheet is pulled physically downwardly into an aperture so that the surface of the sheet which is engageable with the firm and stable support surface is withdrawn from that surface placing two or more fluid passageways in communication. The flexure is all in one direction, that is, downwardly from the horizontal and returned to the horizontal.
Also in accordance with my earlier invention, when the flexible sheet is pulled away from the support surface, it exposes the land which is coincident with the support surface. A space is created, which when filled with a fluid flowing from one channel or passageway, can then flow out the second or additional passageways in communication with the space. It would be desirable if flow across the land could be channeled or directed to permit such flow to take place substantially immediately upon the flexible sheet surface being withdrawn from the support surface rather than waiting for the space to become filled or substantially filled.
It would be desirable if the flexing of the flexible sheet could be reduced to a minimum to avoid undue stress concentration at any one point or points and secondly, to reduce the tendency of the sheet to become stressed beyond its yieldpoint.
It would also be desirable if the solenoid actuated means for physically pulling the flexible sheet downwardly away from the support surface could be replaced with something simpler and equally reliable. Having less bulk and weight and not requiring any adjustment at all, would be a substantial advantage. I have found that fluid pressure and vacuum are ideal for this purpose.
With the above objectives in mind, it has been possible to produce a flexible sheet valve which is lighter in weight, less bulky, less complicated, more reliable and less expensive than those made in accordance with my previous invention.